Method of conserving liquefied gases



' Patented July 5, 1932 nitrogen, ammonia,

UNITED: STATES v PATENT OFFICE CHRISTIAN WILHELH PAUL HEYLANDI', OI BEBLIN-LANKWITZ, enemy, ASSIGN'OR TO FL'UG-A AKTIENGE SELLSCHAIT, OF ST. IOBITZ, SWITZERLAND, A CORPORATION OF SWITZERLAND IETHOD 0F CONSERVING LIQUEFIED GASE No Drawing. Application filed July 17, 1920, Serial 116. 879,076, and in Germany August 4. 1928.

This invention relates to a method of conserving liquefied gases while in storage or transport, particularly liquefied gases of low boiling point, for example liquid oxygen,

methane, and the like.

The invention has for its object generally an improved procedure for charging and operating containers for liquefied gases, that are relativel highly insulated, in such manner that the eat leakage which it is not practical to avoid is absorbed without loss of gas material.

More specifically, a procedure for charging and operating containers of the character indicated, in which the relatively cold body of liquefied gas within the same is arranged to absorb the heat leakage m such a manner as to increase the heat absorbing capacity of such body of liquid to an extent sufiicient to accommodate all takes place in the heat leakage that normallfy time without a predetermined interval 0 increased evolution'of gas.

Heretofore, it was customary to store and transport liquefied gases when handled in large quantities by providing insulated containers which were open to the atmosphere, i. e., such containers. were shipped and transported with the valve open, since it was found that the losses by evaporation ensuing from this practice were less than when the containers were shi ped closed and the liquefied gas transferre to another container at the place of consum tion.

In the practice of the present invention, a transport vessel ofthe lnsulated variety is provided which when fille'd'with the desired quantit of the liquefied gas is closed to the atmosp ere. The heat leakage which it is not practical to avoid is permitted to become absorbed by the body of liquefied gas in the container which, in consequence, becomes artially vaporized and pressure thereupon it is an object to provide vaporization of the manner in which the metho of the present invention may be carried out:

The liquefied gas is placed in a vessel, having heat insulating walls, while under normal atmospheric ressure and at its normal boilin point un er such pressure. In the case 0 oxygen the temperature will be substantial] 182.5 0., for nitrogen it will be substantially 195.8. 0., for ammonia as 38.5 0., and for methane 164.7 0. other gases the boiling points will, of course,

different but the foregoing show examples of the temperatures at which the liquefied gas must be placed in the container. The vessel is then closed whereupon sufiicient of tlie liquefied gas eva orates to raise the pressure on the liquefie gas approximately one atmosphere. This has the effect referred to above of raising the boiling point. In the case of oxygen the boiling point under this additional pressure becomes approximately 0. With other gases the boiling points are raised in like manner, the points attained varying with the particular gas.

'While the boiling'pointpf the liquefied gas an example of a specific the pressure has increased one atmosphere, h

appreciably raised but it is still the same as it was when the 'li uefied gas was" at its normal' atmospheric 1 oiling point; Liquefied gases are well known to absorb heat very slowl so that it will take much time for the liquefied gas in the container to be heated sufliciently to reach the new boiling point which has been indicated by the increase of ressure in the container. Thus, practicaly all of the small quantity of heat leaking into the container will be absorbed by the liquefied gas. There will, therefore be such I a slow increase of pressure and such slow liquefied gas that no excessive pressure .is produced in the container 0 and consequently the as may be transported for long d stances wit out loss.

After the containing vessel is closed, the pressure builds up at a continually decreasing rate. This is in part due to the decrease in specific heat of the liquid which accompanies the elevation of the boiling point with increase in pressure. For example, where the pressure increases by about 1 atmosphere, 'the boiling point is raised from about 182.5 C. to about 170 C. with the result that the quantity of heat thatis absorbed to increase the pressure thereafter does not so readily occur as at the beginning.

The present method is particularly applicable to the storage and transport of liquefied gases such as ammonia and methane, whose latent heats of vaporization have relatively high values. When liquid oxygen or nitrogen are stored or transported in accordance with the present method, they may be retained in ordinary transport vessels for eriods of several days without encountermg substantial losses from evaporation and without recourse to any special heavy construction for the transport-vessels.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is: p p

1. The method of conserving liquefied gases, while in storage or transport, which comprises charging an insulated liquefied gas container with a desired body of liquefied gas, raising the boiling point of said body of liquefied gas by increasing the pressure thereon, and thereafter absorbing the heat leakage which permeates the insulation as sensible heat within said body of liquefied gas.

' 2. The method of conserving liquefied gases, while in storage or transport, which comprises charging an insulated liquefied gas container with a desired body of liquefied gas, causing the gas evolved within said container to increase the pressure on said body of liquid whereby its boiling point is raised, and thereafter absorbing the heat leakage as sensible heat within said body of liquid whereby the gas evolved within said container is made relatively small during a desired period.

3. The method of conserving liquefied gases, while in storage or transport, which comprises charging an insulated liquefied gas container with a desired body of liquefied gas, reducing the rate of latent heat absorption by said body of liquefied gas by reducing the temperature difference between said body and that of the external source, and absorbing the heat leakage which permeates the insulation as sensible heat within said body.

4. The method of conserving liquefied gases, while in storage or transport,which comprises charging an insulated liquefied gas container with a desired body of liquefied gas, closing the communication of the container to the.outer atmosphere for substantially the period of time that said container is to be in storage or transport whereby the pressure nee -51o builds up therein at a continually decreasing rate, and absorbing the heat leakage which permeates the heat within said body.

insulation as sensible 'In testimony whereof I have signed my name to this specification.

CHRISTIAN W nun-2m PAUL nsrunnr. 

